It is known to prepare the esters of an alkyltartronic acids, having formula (I): ##STR1## wherein R is an alkyl or cycloalkyl group and wherein R' and R", said groups being the same or different, are organic groups inert towards the reaction medium, by oxidation of the corresponding alkyl-malonic esters, having formula (II): ##STR2## using, as an oxidizing agent, 98% HNO.sub.3 (see U.S. Pat. No. 3,997,593). It is also known to perform the alkylation of mesoxalic esters, with a Cd-dialkyl compound or with trialkylphosphites (Arbuzov reaction).
Other methods teach how to prepare such esters by hydrolysis of meta-bromo-malonic acid with baryta and subsequent esterification with an alcohol, or by acidic alcoholysis of alpha-cyanolactic acid (pyruvic cyanohydrin) or of 2-acetoxy-2-methyl-malononitrile (1-acetoxy-1,1-dicyano-ethane).
A recent method, teaches how to prepare said esters by hydroxylating methacrylic acid to alpha-methyl-glyceric acid with H.sub.2 O.sub.2, in the presence of H.sub.2 WO.sub.4, and by subsequent oxidation to methyl-tartronic acid, using HNO.sub.3 or O.sub.2 in the presence of either Pd or Pt, followed by an esterification with a suitable alcohol.
The Applicant has now found that it is possible to obtain the alkyl-tartronic esters of formula (I), by direct oxidation of the alkyl-malonic esters of formula (II), without any toxic or dangerous oxidizing agent, such as, e.g., HNO.sub.3, and without any use of noble metals, while performing extremely simple operations.